code: def test_merge_column_with_nulls(repartition):
      # See: https://github.com/dask/dask/issues/7558
  
      df1 = pd.DataFrame(
          {
              "a": [
                  "0",
                  "0",
                  None,
                  None,
                  None,
                  None,
                  "5",
                  "7",
                  "15",
                  "33",
              ]
          }
      )
      df2 = pd.DataFrame(
          {"c": ["1", "2", "3", "4"], "b": ["0", "5", "7", "15"]}
      )
      df1_d = dd.from_pandas(df1, npartitions=4)
      df2_d = dd.from_pandas(df2, npartitions=3).set_index("b")
      if repartition:
          df2_d = df2_d.repartition(npartitions=repartition)
  
      pandas_result = df1.merge(
          df2.set_index("b"), how="left", left_on="a", right_index=True
      )
      dask_result = df1_d.merge(
          df2_d, how="left", left_on="a", right_index=True
      )
  
      assert_eq(dask_result, pandas_result)
  
imports: from __future__ import annotations
  import numpy
  import pandas
  import pytest
  import dask.dataframe
  from dask.dataframe._compat import PANDAS_GE_210
  from dask.dataframe.utils import assert_eq
label_desc: Use image node_id 22 for calling a global function with example usage: test_merge_column_with_nulls(repartition) without return types